I have two questions regarding the phase noise simulation results (PSS + Pnoise) for ring oscillators:
(1) How much the precision of the initial oscillation frequency is important in estimating phase noise ?
(2) The results that I get for the phase noise seems a bit high. I feel there is a shift up in all the frequencies. In very low frequencies (close to carrier) the phase noise is largely positive. Comparing with the analysis presented in [Abidi, JSSC 2006] the phase noise sounds very high. Does someone has any idea that what could be wrong?
The ring oscillator designed to oscillate at 2.4 GHz using CML gates with a tail bias current of about 200 uA.
Thanks in advance for your help.